How to remove/replace the wikitude logo and add the API key to remove 'Beta' watermark? Are there any documentation for this?
By creating your own overlay, the logo will be replaced by your own, as described here: http://www.wikitude.org/enadd-overlay-ar-2
You can get your API key here: http://www.wikitude.org/developers more specifically: http://w4client.mobilizy.mobi/w4/jsp/keyGenerator.jsp
(you might want to try and phrase your question a bit better next time. I had to guess at what you meant. Try and write in complete sentences.)
Hope this helps!